The cost of religion is also divided into different levels. The cost of Christianity is more expensive than that of Islam. Christianity has a large number of full-time and unproductive clergy and churches that need to be supported, while Muslim clergy are all part-time, and Muslims enjoy tax cuts and share costs with secular regimes. Therefore, Muslims are widely spread in those remote places in the Middle East. Of course, the discovery of oil later was God's gift.

Similarly, Buddhism originated in India, but the cost of Buddhist temples and monks was too high. In addition, Buddhism became too metaphysical, with boundless content and out of touch with the masses, so it was gradually defeated by Hinduism in India and gradually took root in East Asia.

China's native superstitions are similar. For example, the local gods believed in by rural areas, such as the Dragon King, Kitchen God, Mazu, etc., are the same. The cost is low. The village can just build a mud house and make a clay statue, and they can receive incense. It is not like Buddhism where you have to buy their high-quality incense.

If you look at the above criteria, it seems that most places with Christianity and Buddhism have become secularized. Perhaps it is because they are relatively wealthy, and supporting Christianity and paying taxes are seamless. On the other hand, Hinduism and Islam may represent the low-cost optimal solution for order. Why is it so difficult for the United States to promote freedom and democracy in Afghanistan? Because the cost is high.